1. Field of the Invention
The invention relates to a device for forming a tube provided with gussets out of a single- or multi-layer, continuously pre-tensed material web having divided upper and lower folding plates that determine the width of the tube when it is laid flat and are mounted on the machine frame, with the web being deflected by the entrance sides of these plates in order to raise the edge regions that are to be driven inwards, which entrance sides may be adjusted in their distance from one another to correspond to the width of the tube to be formed and which plates approach one another with regard to their distance from one another approximately in the shape of a wedge and in a manner perpendicular to the plane of the tube to be formed, beginning from the approach sides, with the wedge angle being adjustable, and with the device having two rows of insertion discs respectively mounted on carriers reaching between the folding plates for forming the gussets, whose distance from one another may be adjusted in the plane of the tube to be formed.
2. Description of the Related Art
One device of this type is known from DE 36 40 219 C1. In the known device, the folding plates and the rows of insertion discs engaging between the folding plates must be adjusted to correspond to the width of the tube to be produced when it is laid flat, and to correspond to the depth of the gussets; here, it must be taken into account that, corresponding to the wedge angle between the folding plates, the rows of insertion discs must approach the material web in the direction of the exit, which requires a particularly expensive adjustment.
The object of the invention is therefore to create a device of the type mentioned at the outset in which the adjustment work required for changing the format of the tube to be formed, i.e., changing the width and/or the depth of the gussets, is simplified.
This object is attained according to the invention in that an adjustment device for adjusting both rows of insertion discs is connected on the middle level between the upper and lower folding plates directly or indirectly to a device for displacing both rows of insertion discs in such a way that the angle formed by the common tangents of the two rows of insertion discs is sufficiently large that the insertion discs essentially firmly supply the interior folding edges of the gussets.
It is useful for the device to comprise gear instruments, for example, lever gears, for displacing both rows of insertion discs.
In the device according to the invention, therefore, the adjustment device for adjusting both rows of insertion discs is connected in a geared manner the middle level between the upper and lower folding plates and/or the holding devices carrying or storing both rows of insertion discs to an adjustment device for displacing both rows of insertion discs in the crosswise direction; they are connected in such a way that the pivoting motion for adjusting the insertion discs in the middle level, i.e., the vertical pivoting motion of both rows of insertion discs in the horizontal middle level, is overlapped with a pivoting motion of both rows of insertion discs in the middle level in such a way that the insertion discs follow the transverse progression of the interior folding edges due to the wedge angle of the folding plates.
In order to adjust both rows of insertion discs on the middle level between the upper and lower folding plates, it is useful for the carriers of both rows to be mounted on two capping pieces that are mounted on the machine frame in the region of the raising of the folding plates such that they may be pivoted around a crosswise axis and that are provided on the approach side with an adjustment device that pivots one of the capping pieces, with the carriers being mounted on the capping pieces such that they may be pivoted around a vertical axis in the exit region and being movable relative to the capping pieces on the approach side in the plane of the insertion discs by means of a lever mechanism that transfers the pivoting motion of the capping pieces onto the carriers. Here, of course, the lever mechanism should be structured in such a way that the pivoting motion of the capping pieces is transferred onto the carriers of both rows of insertion discs such that they perform a pivoting motion that corresponds to the approach of the interior folding edges when inserting the gussets while the material web is traveling over the folding plates.
In accordance with a preferred embodiment, it is provided for the carrier of the rows of insertion discs to consist of L-shaped angle pieces and strip attached to the legs of these pieces running parallel to the folding plates, which legs carry the rows of insertion discs, with the vertical legs of both approach-side angle pieces being provided with horizontal pins that are guided into the bores of the capping pieces in a displaceable fashion, and with the angle regions of angle levers being mounted on the pins, whose legs carry on their ends rollers or sliding blocks which are guided on one side in a horizontal, frame-tight, crosswise guide and on the other side in vertical guides of the capping pieces. Here, the angle between the legs of the angle lever and the length of the legs as well as the guides for the guide device arranged on the end of the legs should be selected such that the desired displacement characteristic is achieved.
An exemplary embodiment of the invention shall be explained in greater detail in the following with reference to the drawings, which show: